Evaluation of peripheral and central olfactory pathways in HIV-infected patients by MRI

Objectives We investigated peripheral and central olfactory pathways in HIV-infected patients by cranial MRI. Methods The cranial MRI images of 37 HIV-infected adult patients and 37 adult subjects without HIV-infection having normal cranial MRI results were included in the study. In both groups, olfactory bulb (OB) volume) and olfactory sulcus (OS) depth; and insular gyrus and corpus amygdala areas were measured in cranial MRI. In the HIV group, disease duration, HIV RNA, and CD4 lymphocyte count and % levels were also recorded. Results The HIV group had significantly lower bilateral OB volumes, insular gyrus and Corpus amygdala areas compared to the control group. The HIV group showed positive correlations between OB volumes, OS depths, insular gyrus and corpus amygdala areas bilaterally. Increases in OB volumes and OS depths were associated with an increase in the insular gyrus area. The Corpus amygdala and insular gyrus areas increased together. There was no significant correlation between age, gender, disease duration, CD4 lymphocyte count and %, HIV RNA values, and the measurement values of the central and peripheral smell regions. Conclusion A decrease in olfactory regions of OB, insular gyrus, and Corpus amygdala in HIV-infected patients shows that HIV infection may cause olfactory impairment. There is no correlation between disease duration and olfactory impairment may be related to neuroinflammation, HIV-related brain atrophy, AIDS Dementia Complex, or neurocognitive impairment which are the other explanations for the olfactory impairment in HIV. The possible toxicity of the ART may be another cause that should be investigated further.